High-Dose Esterified Estrogens in Treating Postmenopausal Women With Metastatic Breast Cancer That Has Failed Previous Hormone Therapy

DISEASE CHARACTERISTICS: Histologically confirmed breast cancer Metastatic disease Documented disease progression Must have received and subsequently failed (due to disease progression) ≥ 2 prior sequential endocrine therapies for treatment of metastatic breast cancer Disease progression during adjuvant tamoxifen is considered 1 prior therapy The 2 most recent treatments must have been endocrine agents At least 1 objective measurable disease parameter Brain metastases allowed provided both of the following criteria are met: Brain metastases were previously treated AND are currently stable Brain metastases are not the only site of metastatic disease Hormone receptor status Estrogen and/or progesterone receptor-positive tumor PATIENT CHARACTERISTICS: Age 18 and over Sex Female Menopausal status Postmenopausal, as defined by any of the following: At least 50 years of age with an intact uterus AND amenorrheic for the past 12 months At least 50 years of age without a uterus AND follicle-stimulating hormone (FSH) level within postmenopausal range Under 50 years of age and FSH level within postmenopausal range Prior bilateral oophorectomy Performance status ECOG 0-2 Life expectancy At least 6 months Hematopoietic Adequate hematologic function Hepatic Adequate hepatic function Bilirubin ≤ 1.5 times upper limit of normal No history of hepatic adenoma Renal Adequate renal function No history of hypercalcemia or severe hypocalcemia Cardiovascular No history of thrombophlebitis or thromboembolic disorders associated with prior estrogen use No active thrombophlebitis or thromboembolic disorders No history of uncontrolled hypertension Other Not pregnant No undiagnosed abnormal vaginal bleeding No other serious medical illness No psychiatric illness that would preclude giving informed consent No other invasive malignancy within the past 5 years except curatively treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix PRIOR CONCURRENT THERAPY: Biologic therapy Not specified Chemotherapy Prior chemotherapy for metastatic disease allowed Prior adjuvant chemotherapy allowed Endocrine therapy See Disease Characteristics Radiotherapy Prior radiotherapy allowed provided the only site of measurable disease was not irradiated Surgery Not specified